Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of the common general knowledge in the field.
There are many methods which have been reported for cleaning surfaces of articles. The method which is chosen to clean a particular surface depends on the nature of soil, the nature of substrate and its surface, and the degree of cleanliness required. The substrates can have porous or non-porous surfaces. Examples of substrates with non-porous surfaces include wood, ceramic, stone, china clay, glass, metals, alloys, semiconductors in the computer industry etc. Materials having porous surfaces include materials made of natural fibers e.g. cotton, silk and materials made of synthetic fibers e.g. polyesters, nylons, acrylics and polyolefins and combinations of natural and synthetic fibers. Natural and synthetic fibers are primarily made into personal clothing, carpets, and upholstery. All of the above materials get soiled as they are used and need cleaning to make it presentable and healthy for the user. The methods used to clean substrates with porous surfaces have generally been different from the methods used to clean non-porous surfaces.
Substrates with non-porous surfaces have generally been cleaned using mechanical/physical methods like scrubbing, buffing, abrasion, ultrasonication or use of chemical methods such as use of surfactants, solvents, acids, alkalis, bleaches and enzymes. Porous surfaces e.g. those of fabrics have generally been cleaned with a combination of chemical and mechanical methods e.g. the fabric is agitated in the presence of a surfactant.
Sprays which are either high speed liquids e.g. water or a combination of water and air have generally been used to clean hard and non-porous surfaces e.g. cleaning automobiles, walls of buildings, metal vessels. Sprays have also been reported to clean semiconductors in the computer industry.
U.S. Pat. No. 4,787,404 (IBM, 1988) disclosed a low flow-rate pressure atomizer device which is so dimensioned and operated as to accelerate a gas to substantially sonic velocity and cause it to break up a cleaning liquid also input at a high pressure into small droplets and accelerate these droplets to at least half the velocity of said gas to create shear stress at a surface adjacent the exit end of said device, thereby to remove the contaminants or the like from said surface.
These and similar devices are directed to cleaning semiconductors and are too complex in design to enable cleaning of everyday objects by a lay consumer. Further the present inventors have determined that the cleaning is not as effective and can be improved further.
Various spray systems have also been reported to clean fabrics. U.S. Pat. No. 4,127,913 (Monson, 1978) describes a fabric cleaning device having a container for cleaning solution, a movable tank for waste water and a cleaning head removably attached to the tank by a vacuum hose for cleaning the fabric. This device requires electric power and a source of pressurized water. Water from the container is directed through a hose to a discharge nozzle mounted in the cleaning head which selectively rinses dirt and cleaning fluid from the fabric. The vacuum pump draws the resulting mixture of cleaning fluid, water and dirt from the fabric and conveys it through the cleaning head to the tank. This system is directed to industrial cleaning where the fabric after treatment with the cleaning solution requires additional equipments for removal of the dirty water by means of vacuum.
An equipment, having similar limitations has been disclosed in U.S. Pat. No. 5,001,806 (US Products, 1991). The fabric cleaning apparatus here includes a vacuum hose and a liquid spray nozzle provided on a universal head support for accepting any one of a series of different sized and/or shaped cleaning head attachments, each being adapted for a particular fabric cleaning function.
US2003205631 (Procter and Gamble) discloses a method and equipment for applying a liquid product onto a household article or plant for purpose of cleaning, wetting, coating, polishing, fabric treatment, plant watering and the like, the method comprising discharging the liquid through a spray nozzle in the form of an upwardly or downwardly directed spray of droplets having an average droplet size of at least about 40 microns and at a proximal distance of from about 0.1 to about 1 m from the household article or plant, the liquid being discharged through the spray nozzle at an exit velocity in the range from about 3 to about 80 m/s and at an applied potential in the range from about 0.2 to about 50 kV, whereby the overspray is less than about 40%. The equipment preferably comprises a nozzle having a multi-jet spray head, means for adjusting the orientation of the nozzle and grounding means for charge dissipation. This invention is for household use, it is directed to ensuring efficient coverage of the substrate and does not provide effective cleaning in itself.
U.S. Pat. No. 7,021,571 (Procter and Gamble, 2006) relates to a portable device for spraying a liquid at low pressure, said device comprising a spray arm and characterized in that the spray arm comprises at least one flat fan spray nozzle. Preferably, the liquid is a cleaning composition for treatment of carpets and other large fabric coverings, more preferably, a composition comprising surfactants. Also preferably, the portable device is electrically driven, and/or the spray arm is extendible and/or detachable from the device's main unit. This device is directed to ensure even coverage of the substrate e.g. carpets with the cleaning fluid and complete cleaning can be ensured only with a further downstream operation like vacuuming. It does not provide for cleaning in a single operation.
Thus there is a need in the art for providing for a convenient, preferably hand-held and/or portable device which can clean soiled fabric in a relatively short time while ensuring that there is minimal fabric damage.
It is thus an object of the present invention to provide for a process to clean soiled fabric with a hand held device in faster time as compared to some of the processes reported in the past.
It is another object of the present invention to provide for a process to clean soiled fabric which does not necessarily require an additional cleaning step like agitation in water, vacuuming or brushing.
It is yet another object of the present invention to provide for a process to clean soiled fabric which utilizes relatively lower amount of water for the cleaning operation, as compared to some of the prior art.
It is yet another object of the invention to provide for a device to clean soiled fabric which meets one or more of the above process objects in a simple, convenient, and/or easy to handle household device.